1) First upload the image to us by clicking "Add Image"
2) Browse to the image on your PC. Select the image and press "OK"
3) Now left click on the image in the editor and hold the mouse button down. Any image boxes will show a message indicating that you can insert your image there. If you drag the image to a text box, any place an image can be inserted will display a message indicating this when you drag the image over it.
4) When you let go of the mouse button it may take a moment for the editor to insert the image. Once inserted you will see the image in your email.